The Neuron: Characteristics And Functioning

The neuron is the fundamental functional unit of the nervous system. Our behavior and our cognition ultimately depend on how they function and how each neuron is able to relate to its “partners.” These small nerve cells are what make up our biological substrate on a psychological level, the basis of our emotions and thoughts.

First of all, it is essential to know that all neurons have the same genetic information as the rest of the cells of the body and that in addition they have the same fundamental elements in their structure (membrane, nucleus, organelles, etc.). What gives it its differentiation from other cells is the place they occupy in the neural network. This allows them to carry out the basic processes of receiving, processing and transmitting information.

To understand what a neuron is, it is very important to know what its structure and synaptic function are like. Both aspects will help us to understand why they are grouped the way they do and how they transmit information through the brain. For this reason, in this article we are going to explain the structure of the neuron and the synapse.

Neuron structure

Although there are different types of neurons with different structures, common elements can be found between them. The type structure is one that is formed by three fundamental parts: the soma, the dendrites and the axon. This anatomy allows it to fulfill its connectivity and information management functions.

Before explaining each of the parts, it is interesting to mention the peculiarity of its membrane. Its permeability is different from that of other cells in the body, which allows them to respond to stimuli from their environment. Thanks to this, the electrical impulse generated in it can travel to other cells or tissues.

Parts of the neuron

The central part of the neuron is the soma, the place where all metabolic activity takes place. The soma contains the cell nucleus along with another series of cellular microstructures and organelles, responsible for keeping the neuron alive.

Dendrites are branches that arise from the neuronal soma and give the nerve cell an arboreal appearance. These constitute the main area for receiving information. The dendritic tree has several bifurcations that allow a neuron to connect to the axons of other neurons and thus communicate with them. The information is transmitted thanks to the fact that the dendrites have a series of neuroreceptors along their membrane. Although communication is commonly axon-dendrite, other types can also occur (axon-axon or axon-soma).

The axon arises from the soma from a thick segment called the axon cone. The function of this is to integrate all the information captured by the neuron, and then transmit it to others. At the end of the axon there are what are called terminal buttons, which are responsible for connecting with the dendrites of other neurons.

Synapse or neuronal communication

Once we have understood what the structure of the neuron is like, it is essential to understand how they communicate with each other. The communication of neurons takes place through the synapse. This usually occurs through the axon-dendrite connection, but as mentioned above, other types of communications can occur.

At a morphofunctional level, communication is classified into electrical synapses or chemical synapses. And although various electrical synapses can be found, especially at smooth muscle connections, the vast majority of synapses in the mammalian nervous system are chemical in nature.

Structures called connexins are involved in electrical synapses, which are ion channels that join neurons and allow the passage of electrical current between them. The advantage of this synapse with respect to chemistry is the lack of delay in the transmission of information. The downside of this is that the quality and capacity of the information is much poorer than in other types of synapses.

In chemical synapses, the essential aspect is the existence of substances called neurotransmitters or neuromodulators  (such as dopamine). These substances are stored in the axon terminal, waiting for the order to be released. Once detached in the interstitial space of two neurons, these neurotransmitters latch onto a series of receptors that modulate neuronal activity. There are a multitude of neurotransmitters, each with different consequences and functioning.

The in-depth study of the structure and synapses of neurons helps us to explain a multitude of processes. Thanks to research, in neuroscience we have come to know in depth the neural mechanisms of learning, perception, emotion, etc.